Increased activity reduces the prevalence of woody breast in Ross 708 and Ranger Gold broilers.

ABSTRACT

Woody or wooden breast (WB) is characterized by hardening and paleness of the Pectoralis major muscle and can affect up to 85% of broilers. We hypothesized that increased locomotor activity would lead to a lower prevalence of WB and increased tibia bone quality, with a greater effect on a faster growing than a slower growing broiler strain. Ross 708 (N = 188) and Ranger Gold (N = 213) broilers were raised in 3.05×3.05 m2 pens in groups of 23 to 24 and 26 to 27, respectively. Target ages for the Ross 708 and Ranger Gold birds were 42 and 56 d. There were 8 pens per strain 4 assigned to an exercise treatment and 4 unexercised controls. An exercise regimen was applied for 10 min every hour for 6 h during each weekday with the goal of increasing frequency of standing and walking. A perch was placed between the feeder and drinker line in the exercise treatment pens to further promote broiler activity. WB severity was determined by palpation for all birds at the target age. Tibial bone mineral content (BMC) and bone mineral density (BMD) were measured using a dual-energy x-ray absorptiometry. The Fisher's Exact Test was used to determine treatment effects on the prevalence and severity of WB. Both prevalence (Ross 708 77.5 vs. 90.5% control, P = 0.013; Ranger Gold 57.9 vs. 76.4% control, P = 0.005) and severity (Ross 708 12.9 vs. 24.2% control, P = 0.02; Ranger Gold 4.7 vs. 0.02% control, P = 0.01) were reduced by treatment. The effects of strain, treatment and their interaction on tibial BMC and BMD were analyzed using linear mixed models. Only strain affected BMC (P = 0.003) and BMD (P = 0.03), with Ross 708 broilers having higher BMC (control 3.246 g ± 0.061; treatment 3.251 g ± 0.058) and BMD (control 0.177 g/cm2 ± 0.002; treatment 0.174 g/cm2 ± 0.002) values compared to Ranger Gold's BMC (control 2.966 g ± 0.067; treatment 2.987 g ± 0.064) and BMD (control 0.168 g/cm2 ± 0.002; treatment 0.168 g/cm2 ± 0.002) values. However, per unit of final body weight, Ranger Gold birds had a significantly higher BMC (P = 0.006) and BMD (P = 0.01) than Ross 708 broilers. Promoting broiler activity can reduce the prevalence and severity of WB prevalence in fast and slow growing broilers.